BACKGROUND: Intravenous cyclophosphamide (IVCY) has been used to treat severe lupus nephritis (LN) for many years. Because of the wide variety of manifestations of the condition and the long-term nature of the disease, outcomes vary widely. OBJECTIVE: To evaluate and compare the immediate and long-term results of IVCY in pediatric onset severe LN and between patients with normal and abnormal initial renal function. METHODS: Patients aged <18 years who attended the Department of Pediatrics, Prince of Songkla University, diagnosed with severe LN, and who were given a 36-month IVCY course, were included. Comparison of overall survival between the two groups was assessed using Kaplan-Meier survival curves. RESULTS: 108 patients with a mean age of 12.6 ± 2.7 years were studied, with a mean follow-up time of 5.7 ± 4.3 years. 48 patients completed the IVCY course. 36 patients had abnormal renal function and 72 patients had normal renal function at the start of therapy. Both groups responded well initially to treatment; proteinuria reduced to normal levels after 1 and 2 treatments in the normal and abnormal groups, respectively, while creatinine clearance returned to normal levels after 8 treatments in the abnormal group. Overall survival was not different between the two groups; however, the abnormal renal function group had a higher crude mortality rate than the normal group (13/36 vs 10/72, p value = 0.02). At the time of analysis, some patients who had completed their IVCY course still required other therapy to control their disease activity. CONCLUSION: Three years of IVCY treatment provided similar outcomes in both normal and abnormal renal function groups. Immediate outcomes were favorable but long-term remission was not promising.